I just installed a pair of EV LS12's in my open baffles in place of the 10" Jensens I was using. These are, indeed, very smooth fullrange drivers, with excellent extension to 10 or 11 kHz. The high Qts (around 1 or so) make them ideal for OB use. The sound good down to about 63 Hz, where they roll off fast. The sound is noticably better the the old Jensens (which sounded pretty good in their own right). This is the first whizzer speaker I've had that the whizzer seems to call no attention to it's self. I can't hear it doing anything that doesn't sound musically right.
I think these speakers are keepers.
Very happy Dave

These are vintage late fifties/early sixties drivers with the old type AlNiCo magnets. They are high Qts, so are perfect for open baffle use. You can find them on ebay frequently for well under $200 a pair. Mine had some small repaired cracks, so I got them cheap at $40 for the pair.
I have bass drivers on the open baffle, and a transformer coupled modded piezo crossed at 12 kHz for highs.
There are pics on my webpage of my open baffles with my old 10" Jensen's. I just cut the holes bigger and mounted the 12" EV's.